1. Technical Field
The present invention relates to a substrate processing apparatus and a substrate processing system having a supply device for a liquid material connected to the substrate processing apparatus, and more particularly, to a vaporizing unit for vaporizing a liquid material or a cleaning system for a liquid material supply device having the vaporizing unit.
2. Description of the Related Art
When a high-permittivity film such as HfO2 and ZrO2 is formed, a material which is liquid at room temperature and atmospheric pressure is mainly used. When a liquid material is supplied to a reaction chamber, it is necessary to vaporize the liquid material using a vaporizer.
As the vaporizer, there is a method for bubbling using an inert gas to supply, and a method for heating and vaporizing to supply. The method for heating and vaporizing is more widely used recently because a greater supply amount can be secured.
FIG. 1 shows a schematic configuration of a heating and vaporizing type vaporizer 242. A liquid material supplied by a liquid material inlet 21 is mixed with a carrier (an inert gas such as N2) supplied from a carrier inlet 27. Then, the liquid material passes through a material introducing pipe 22 and is vaporized in a vaporizing chamber 24 heated by a heater 23, and is sent into a reaction chamber through a vaporized material outlet 25.
Among materials which can be used, TEMAH (Hf(NEtMe)4) has high reactivity with moisture, thereby reacts with moisture included in a carrier N2. This facilitates the creation of a by-product 26, and may cause clogging of a pipe or may cause particles. There are many liquid materials which have extremely high reactivity with moisture or which are easily autolyzed when heated.
Due to such factors, a portion of the liquid material is decomposed in the vaporizing unit and various problems may occur owing to such decomposed matters in some cases. When the boiling point of the decomposed matter (by-product) due to moisture or heat is higher than the boiling point of the original liquid material, the decomposed matter is not vaporized in the vaporizing unit, becomes liquid or solid, and is deposited in the vaporizing unit.
The residual material becomes a generation source of dust, or adheres to a surface of an inner wall of the vaporizing unit, lowers the temperature of the vaporizer to deteriorate the vaporizing performance, or narrows a flow passage to hinder the gas flow. Therefore, it is necessary to overhaul the vaporizing unit within a short period.
FIG. 8 shows a reaction mechanism when a film is formed by an ALD method (reference: D. M. Hausmann, E. Kim, J. Becker and R. G. Gordon, Chem. Matter 14 (2002) 4350-4358). For example, when a material is Zr(NMe2)4, first, the Zr(NMe2)4 is adsorbed in Si—OH on a substrate and Me2N—H is separated. Then, when H2O is used as oxidizer, Me2N— which is attached to Zr is separated as Me2N—H by substitution reaction with H2O and Zr—OH is formed. If H2O is included in a carrier gas, since Zr(NMe2)4 and H2O exist at the same time, a cluster such as (NMe2)n(OH)mZrOl is formed and this causes particles.